1. Field of the Invention
The present invention relates to a semiconductor memory device.
2. Description of the Prior Art
As the FIFO (First In First Out) memory device, for example, two commercial products are known under names, .mu.PD41101C and CXK1202S, respectively. Also some FIFO memory devices have been disclosed in the last 1986 national conference of the Institute of Electronics and Communication Engineers of Japan. When disclosed, all these devices are designated as the line memory. Though characterized by fast operation with read and write cycles as short as around 30 nsec, these devices have modest storage capacities of about 2 kbits per port at most.
To increase the storage capacity, the circuit configuration of memory elements must be simplified as much as possible to allow for higher circuit integration. Being designed for a memory configuration similar to the static RAM (Random Access Memory), however, the above FIFO memory devices, though simple to control for read and write and capable of readily achieving high speed operation, have a problem with respect to high circuit integration.